Warriors are not necessarily easier to heal than druids. It depends on the attack speed and average damage on the boss in question. What makes warriors easier to heal on a lot of ICC content is that the bosses swing quickly and don't hit so hard. A critical block can completely negate almost a full swing. Blocking has gone from laughable (ulduar) to highly effective on some of the new content.
If we were in Ulduar 2.0 with ICC bosses swinging hella slow for 40k hits on plate, the story would change again.
The diffirences between warriors, druids, dks, and paladins don't have much bearing on EH vs. Avoidance arguments. Paladins survivability isn't over-tuned because they have lots of avoidance (though their avoidance levels are similar to mine as a dk, unless is spec frost) it's over-tuned because they have tremendous EH via. ardent defender and a fairly consistant (though no-longer 100%) chance to block a good chunk of attacks that land.